Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/026—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/46—Other types characterised by their X-ray diffraction pattern and their defined composition
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/46—Other types characterised by their X-ray diffraction pattern and their defined composition
  • C01B39/48—Other types characterised by their X-ray diffraction pattern and their defined composition using at least one organic template directing agent

Definitions

• the present invention relates to a method for producing zeolite.
• Zeolite is a crystalline aluminosilicate with uniform pores due to its crystalline structure. Taking advantage of this characteristic, zeolites are used industrially as molecular sieve adsorbents that adsorb only molecules of a specific size, adsorption separation agents that adsorb molecules with strong affinity, and catalyst substrates. For example, BEA-type zeolites are used as catalysts in the petrochemical industry and as catalysts for purifying exhaust gases.
• BEA type zeolite was synthesized using an organic structure directing agent (OSDA).
• OSDA organic structure directing agent
• BEA type zeolite synthesized without using an OSDA contains a lot of Al in the framework and tends to have a low SiO 2 /Al 2 O 3 molar ratio. Zeolites with a low SiO 2 /Al 2 O 3 molar ratio are characterized by high ion exchange capacity.
• Patent documents 1 and 2 disclose a process for dealumination of zeolite by acid treatment and/or steam treatment.
• an object of the present invention is to provide a method for producing a zeolite in which the SiO 2 /Al 2 O 3 molar ratio can be adjusted while maintaining the acid strength and the crystallinity.
• the present invention proposes a method for producing zeolite, which includes the steps of preparing zeolite, mixing the zeolite with water to prepare a zeolite mixture, and continuously supplying a solution containing an inorganic acid to the zeolite mixture.
• the present invention can provide a method for producing a zeolite that can adjust the SiO 2 /Al 2 O 3 molar ratio while maintaining high acid strength and high crystallinity.
• Example 1 shows X-ray diffraction spectra of the BEA zeolites obtained in Example 3 and Comparative Example 2.
• 1 shows the relationship between the acid strength and the amount of acid per mole of Al of the BEA zeolites obtained in Example 1 and Comparative Example 2.
• 1 shows an NMR spectrum of the BEA zeolite obtained in Example 3.
• 1 shows the NMR spectrum (enlarged) of the BEA zeolite obtained in Example 3.
• a step of preparing a zeolite mixing the zeolite with water to prepare a zeolite mixture; continuously supplying a solution containing an inorganic acid to the zeolite mixture.
• [4] The method for producing a zeolite according to any one of [1] to [3], wherein the inorganic acid is supplied in a total amount of 200 g or more per 1,000 g of the zeolite.
• [5] The method for producing a zeolite according to any one of [1] to [4], comprising continuously supplying the solution containing an inorganic acid, and then retaining the zeolite and the inorganic acid without separating the solution containing an inorganic acid from the zeolite.
• [6] The method for producing a zeolite according to any one of [1] to [5], wherein the zeolite to be prepared has a SiO 2 /Al 2 O 3 molar ratio in the range of 3 or more.
• [7] The method for producing a zeolite according to any one of [1] to [6], wherein the zeolite to be prepared is synthesized without using an organic structure-directing agent.
• [8] The method for producing a zeolite according to any one of [1] to [7], wherein the zeolite to be prepared has one type of framework structure selected from the group consisting of BEA type, GIS type, MSE type, FAU type, and LTA type.
• the method for producing zeolite of the present invention includes preparing zeolite, mixing the zeolite with water to prepare a zeolite mixture, and continuously supplying a solution containing an inorganic acid to the zeolite mixture.
• a solution containing an inorganic acid is continuously supplied to the zeolite mixture, so that the zeolite reacts gently with the inorganic acid.
• Al not contained in the framework structure and tetracoordinated Al contained in the framework structure, which is relatively difficult to function as an acid site, are preferentially dissolved, and tetracoordinated Al, which is relatively easy to function as an acid site, tends to remain in the framework structure.
• the acid site adjacent to the Al atom in the framework structure of the zeolite becomes a Brönsted acid site.
• the acid site formed by the tetracoordinated Al in the zeolite has a strong acid strength, and when hydrocarbons are adsorbed, for example, it becomes an active site for the reaction when purifying the adsorbed hydrocarbons.
• the 3-coordinated Al becomes a Lewis acid site, and is an acid site other than the acid site that is the center of the catalytic activity.
• the tetracoordinated aluminum which becomes a Brönsted acid site with a strong acid strength, remains in the framework structure and becomes the center of the catalytic activity.
• a zeolite with a high SiO2 / Al2O3 molar ratio can be prepared from a zeolite with a low SiO2 / Al2O3 molar ratio.
• the solution containing an inorganic acid preferably has a pH of 5 or less at room temperature (e.g., 25°C).
• room temperature e.g. 25°C.
• the solution containing an inorganic acid continuously supplied to the zeolite mixed solution preferably has a pH of 5 or less in order to allow the zeolite and the inorganic acid contained in the solution to react gently, and may have a pH of 3 or less, 1 or less, -2 or more, or -1.5 or more.
• the rate at which the solution containing an inorganic acid is continuously supplied to 1000 g of zeolite contained in the zeolite mixture is preferably 3.0 mL/min or less, more preferably 2.5 mL/min or less, even more preferably 2.0 mL/min or less, and even more preferably 1.8 mL/min or less.
• the rate at which the solution containing an inorganic acid is continuously supplied to 1000 g of zeolite contained in the zeolite mixture is 3.0 mL/min or less, the zeolite and the inorganic acid react gently, and the SiO 2 /Al 2 O 3 molar ratio can be adjusted while maintaining high acid strength and high crystallinity.
• the concentration of the inorganic acid in the solution containing the inorganic acid that is continuously supplied to the zeolite mixture is preferably 50% by mass or more, may be 60% by mass or more, 70% by mass or more, 75% by mass or more, 100% by mass or less, or may be 98% by mass or less.
• the total mass of inorganic acid added to 1000g of zeolite is preferably in the range of 200g or more, more preferably in the range of 250g or more, even more preferably in the range of 300g or more, and even more preferably in the range of 325g or more.
• the total mass of inorganic acid can be adjusted according to the SiO 2 /Al 2 O 3 molar ratio of the target zeolite and the supply speed, so there is no upper limit, but it may be, for example, 1500g or less, 1250g or less, or 1150g or less.
• the inorganic acid and zeolite can be reacted gently by continuously supplying a solution containing inorganic acid to the zeolite mixed liquid, and a zeolite with an adjusted SiO 2 /Al 2 O 3 molar ratio can be obtained while maintaining high acid strength and high crystallinity.
• the temperature of the zeolite mixture when the solution containing the inorganic acid is continuously supplied is preferably 80°C or higher, and may be 90°C or higher, or may be 100°C or higher. If the temperature of the zeolite mixture when the solution containing the inorganic acid is continuously supplied is 80°C or higher, the zeolite and the inorganic acid tend to react more gently.
• the zeolite and the inorganic acid can react more easily.
• There are no particular limitations on the method for continuously supplying the solution containing an inorganic acid and examples of such methods include constant volume delivery and dripping. It is preferable to change the stirring speed of the zeolite mixture depending on the volume of the zeolite mixture and the amount of zeolite in the zeolite mixture, and can be, for example, 5 rpm or more and 300 rpm or less.
• the time for continuously supplying the solution containing an inorganic acid depends on the supply rate, but may be 1 hour or more, 2 hours or more, 3 hours or more, 3.5 hours or more, 40 hours or less, or 38 hours or less. If the time for continuously supplying the solution containing an inorganic acid is 1 hour or more and 40 hours or less, the inorganic acid and the zeolite react gently, and Al, which is relatively difficult to function as an acid site, is preferentially eluted from the framework structure, and a zeolite with an adjusted SiO2 / Al2O3 molar ratio can be obtained while maintaining high acid strength and high crystallinity.
• the inorganic acid can be any known acid used for the dealumination of zeolites without any particular restrictions.
• at least one acid selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and mixtures of two or more thereof can be used.
• the time for which the zeolite and the inorganic acid are held without separating the inorganic acid-containing solution from the zeolite after the solution containing the inorganic acid is continuously supplied to the zeolite mixed solution can be adjusted according to the SiO2 / Al2O3 molar ratio of the target zeolite.
• the time for which the zeolite and the inorganic acid are held may be 1 hour or more, 2 hours or more, 3 hours or more, 15 hours or less, or 12 hours or less.
• the time for which the zeolite and the inorganic acid are held without separating the inorganic acid-containing solution from the zeolite after the solution containing the inorganic acid is continuously supplied to the zeolite mixed solution is also referred to as the "aging time".
• stirring may or may not be performed. If stirring is performed, the stirring speed can be, for example, 5 rpm or more and 300 rpm or less.
• a process of continuously supplying a second solution containing an inorganic acid may be carried out.
• the process of continuously supplying a second solution containing an inorganic acid may be carried out under the same conditions (concentration, amount, speed, time) as the first continuous supply, or the conditions do not have to be the same.
• a further aging process may be carried out.
• the zeolite to be prepared preferably has a SiO 2 /Al 2 O 3 molar ratio of 3 or more. If the SiO 2 /Al 2 O 3 molar ratio of the zeolite to be prepared is 3 or more, the SiO 2 /Al 2 O 3 molar ratio can be adjusted to a higher value by continuously supplying a solution containing an inorganic acid to the zeolite mixed liquid and reacting the zeolite with the inorganic acid.
• the SiO 2 /Al 2 O 3 molar ratio of the zeolite to be prepared may be 5 or more, 8 or more, or 9 or more.
• the SiO 2 /Al 2 O 3 molar ratio of the zeolite to be prepared there is no particular limit to the upper limit of the SiO 2 /Al 2 O 3 molar ratio of the zeolite to be prepared, but it is preferable that the zeolite contains a large amount of aluminum from the viewpoint of preparing a zeolite with a wide range of SiO 2 /Al 2 O 3 molar ratios by removing the aluminum contained in the zeolite.
• the SiO 2 /Al 2 O 3 molar ratio may be not more than 500, not more than 400, or not more than 350.
• the SiO 2 /Al 2 O 3 molar ratio of the zeolite can be calculated from the Si and Al amounts obtained by measuring the Si and Al amounts by elemental analysis or ICP emission spectroscopic analysis using a fluorescent X-ray analyzer (e.g., ZSX Primus II, manufactured by Rigaku Corporation).
• a fluorescent X-ray analyzer e.g., ZSX Primus II, manufactured by Rigaku Corporation.
• the zeolite to be prepared is preferably one synthesized without using an organic structure directing agent (OSDA).
• OSDA organic structure directing agent
• Zeolite synthesized without using an OSDA does not require the removal of the OSDA, and the energy and cost required for removing the OSDA can be reduced.
• Zeolite synthesized without using an OSDA has few defects and contains a large amount of aluminum, with a SiO 2 /Al 2 O 3 molar ratio of 3 or more.
• the zeolite framework structure to be prepared is not particularly limited.
• BEA type, GIS type, MSE type, FAU type, MFI type, MTW type, PAU type, MAZ type, VET type, NES type, MOR type, MWW type, and LTA type can be mentioned.
• the zeolite has one type of framework structure selected from the group consisting of BEA type, GIS type, MSE type, FAU type, and LTA type.
• Zeolite has a crystalline or quasi-crystalline aluminosilicate crystal structure composed of repeating units of SiO 4 and AlO 4 tetrahedrons.
• the unit forming the framework structure of zeolite may be described as TO 4 unit.
• the framework structure of zeolite is given a three-letter structure code defined by the International Zeolite Society. If the zeolite to be prepared has one type of framework structure selected from the group consisting of BEA type, GIS type, MSE type, FAU type, and LTA type, by continuously supplying a solution containing an inorganic acid to the zeolite mixture, the inorganic acid and the zeolite react gently, and Al, which is relatively difficult to function as an acid site, is preferentially eluted from the framework structure, thereby maintaining high acid strength and high crystallinity, and making it easier to adjust the SiO2 / Al2O3 molar ratio higher.
• the zeolite to be prepared is preferably one having a 12-membered ring skeletal structure such as BEA type zeolite.
• a 12-membered ring skeletal structure such as BEA type zeolite.
• the zeolite to be prepared has a 12-membered ring skeletal structure, even bulky molecules can be adsorbed in the pores of the zeolite.
• the zeolite to be prepared has a 12-membered ring skeletal structure, it is relatively easy to remove aluminum contained in the zeolite, and it is possible to prepare zeolites having a wide range of SiO2 / Al2O3 molar ratios while maintaining high acid strength and high crystallinity, thereby expanding the range of use.
• the zeolite to be prepared may be at least one type of zeolite selected from the group consisting of proton-type zeolite ion-exchanged with hydrogen ions, sodium-type zeolite ion-exchanged with sodium ions, and ammonium-type zeolite ion-exchanged with ammonium ions.
• the zeolite to be prepared may be contacted with water or an aqueous solution containing sodium ions or ammonium ions to obtain each cation type zeolite, or ammonium ion-type zeolite may be heated to obtain proton-type zeolite.
• the water to be mixed with the zeolite is preferably deionized water or pure water.
• concentration of the zeolite mixture there are no particular limitations on the concentration of the zeolite mixture, and it can be adjusted as appropriate depending on the amount of zeolite to be prepared and the scale of the production equipment.
• the zeolite is separated from the resulting treated mixture.
• the zeolite separated from the mixture may be washed, dried, or calcined.
• the zeolite may be separated by a method such as filtration, ultrafiltration, diafiltration, or centrifugation.
• the separated zeolite may be washed with water, alcohol such as methanol, ethanol, or propanol, or a mixture thereof.
• the washed zeolite may be dried, and the drying may be performed as long as the moisture can be removed.
• the zeolite may be dried in the air at a temperature of 50°C to 120°C for 3 hours to 25 hours.
• the drying may be performed using a dryer such as a fluidized bed dryer or a spray dryer.
• the SiO 2 /Al 2 O 3 molar ratio of the resulting treated zeolite is preferably within the range of 13 to 1,000.
• the inorganic acid reacts with the zeolite slowly, and Al, which is relatively difficult to function as an acid site, can be preferentially eluted from the framework structure. This allows a zeolite having a wide range of SiO 2 /Al 2 O 3 molar ratios to be obtained while maintaining high acid strength and high crystallinity.
• the SiO 2 /Al 2 O 3 molar ratio of the treated zeolite obtained after continuously supplying a solution containing an inorganic acid to the zeolite mixture may be in the range of 14 to 800, 700 or less, 600 or less, 500 or less, or 400 or less.
• Zeolites with a high SiO 2 /Al 2 O 3 molar ratio have high hydrothermal durability. Hydrothermal durability indicates the resistance of the crystal structure to destruction when exposed to high temperatures in the presence of water vapor.
• Zeolites with a low SiO 2 / Al 2 O 3 molar ratio have a large amount of Al in the framework of the zeolite.
• the SiO2 / Al2O3 molar ratio of the obtained zeolite can be measured by the same method as that for the above-mentioned prepared zeolite.
• the zeolite prepared is a BEA type zeolite
• the zeolite obtained after continuously supplying a solution containing an inorganic acid to the zeolite mixture is a BEA type zeolite
• the apex of the peak due to adsorption to the acid sites of the BEA type zeolite in the NH 3 -TPD spectrum of the BEA type zeolite when heated at 10°C/min by ammonia temperature programmed desorption method (NH 3 -TPD method) is in the range of 340°C or more and 500°C or less
• the ratio A/B of the maximum diffraction intensity A of the peak of the BEA type zeolite to the diffraction intensity B of the (111) plane of Si which is the standard material 640c distributed by the National Institute of Standards and Technology, is 25 or more.
• the temperature of the obtained BEA zeolite is raised at 10°C/min by the ammonia temperature programmed desorption method (NH 3 -TPD method)
• NH 3 -TPD method ammonia temperature programmed desorption method
• the apex of the peak due to adsorption to the acid sites of the BEA zeolite in the NH 3 -TPD spectrum of the obtained BEA zeolite is in the range of 350°C or more and 500°C or less, and even more preferable that it is in the range of 350°C or more and 450°C or less.
• the obtained BEA type zeolite preferably has a ratio A/B of 25 or more of the maximum diffraction intensity A of the peak of the BEA type zeolite to the diffraction intensity B of the (111) plane of Si, which is the standard material 640c distributed by the National Institute of Standards and Technology, in an X-ray diffraction spectrum measured by an X-ray diffraction method using CuK ⁇ radiation.
• the ratio A/B is an index of the crystallinity of the BEA type zeolite. When the ratio A/B is 25 or more, a high degree of crystallinity is maintained and the crystal structure is stable.
• the ratio A/B is more preferably 27 or more, even more preferably 33 or more, even more preferably 35 or more, and particularly preferably 40 or more, and may be 200 or less, 150 or less, 100 or less, or 80 or less.
• the X-ray diffraction spectrum of BEA-type zeolite can be measured using an X-ray diffractometer (e.g., RINT-TTR III, manufactured by Rigaku Corporation) with CuK ⁇ radiation (0.15406 nm, 50 kV, 300 mA) as the X-ray source.
• the area ratio P1/(P1+P2) of the area of peak 1 to the sum of the areas of peak 1 and peak 2 is in the range of 0.4 or more and 1.0 or less, and it is preferable that the ratio A/B of the maximum diffraction intensity A of the peak of the BEA-type zeolite to the diffraction intensity B of the (111) plane of Si, which is the standard material 640c distributed by the National Institute of Standards and Technology, in an X-ray diffraction spectrum measured by an X-ray diffraction method using CuK ⁇ rays, is 25 or more.
• the 27 Al MAS NMR spectrum of the obtained BEA zeolite can be measured, for example, under the following conditions.
• Standard for chemical shift value The central peak of potassium alum is set to ⁇ 0.21 ppm.
• Radio frequency pulse intensity The intensity is set to a value that makes the pulse width 4.5 ⁇ s, which maximizes the potassium alum peak when the spectrum center is 51.675 ppm.
• Radio frequency pulse width 2.5 ⁇ s
• Measurement interval 10.4 ⁇ s (converted to 5.2 ⁇ s in the value indicated by the symbol DW on the software mentioned above)
• Number of measurement points 961 points (converted to 1922 when expressed as the symbol TD in the software mentioned above)
• Number of spectrum points (symbol SI on the above software): 4096 points Number of integrations (symbol NS on the above software): 3200
• the spectrum obtained as described above is subjected to baseline correction using calculation software to obtain an 27Al MAS NMR spectrum.
• the baseline is created by connecting point Q1, which is the arithmetic mean of the chemical shift values and signal intensities of all points from the point closest to 90 ppm to the point closest to 100 ppm, with point Q2, which is the arithmetic mean of the chemical shift values and signal intensities of all points from the point closest to -50 ppm to the point closest to -40 ppm.
• the spectrum obtained as described above is called the "measured Al spectrum”. Peak 1 and Peak 2 are peaks obtained by separating the measured Al spectrum.
• Peak separation is performed by fitting a calculated spectrum created by the sum of two pseudo Voigt functions to the measured Al spectrum in the range from the point closest to the 27Al chemical shift value of -40 ppm to the point closest to 90 ppm (hereinafter, for convenience, this is referred to as the range of -40 ppm to 90 ppm).
• the pseudo Voigt function is the sum of a Lorentzian function and a Gaussian function with the same full width at half maximum.
• the pseudo Voigt function f(x) used in peak separation is shown in Equation (1) below.
• the peak area of each peak is calculated by the sum of the signal intensities of the peaks calculated by the pseudo Voigt function at points in the range of -40 ppm to 90 ppm of the measured Al spectrum.
• the chemical shift value x0 of the peak apex obtained by fitting with this pseudo-Voigt function is referred to as the "chemical shift value of the peak apex" of peak 1 and peak 2.
• the fitting is performed until the ratio of the mean square error D0 between the measured spectrum and the spectrum calculated as the sum of all peaks (hereinafter referred to as the "calculated spectrum") for the maximum value Y0 in the range of the chemical shift of the measured spectrum from -40 ppm to 90 ppm, D0/Y0, is 0.01 or less.
• D0/Y0 is not 0.01 or less, one or more peaks whose chemical shift at the peak apex is in the range of more than 59.0 ppm and less than 90 ppm, and one or more peaks whose chemical shift at the peak apex is in the range of more than -40 ppm and less than 45 ppm are added. If D0/Y0 becomes 0.01 or less by adding this peak, no peak is added, and if D0/Y0 is greater than 0.01, the above operation is repeated.
• the "pseudo-Voigt function” is based on “6. Profile functions and pattern decomposition methods" in “Special feature: New developments in powder diffraction methods" in Journal of the Crystallographic Society of Japan 34, 86 (1992).
• peak 1 has a chemical shift value of the peak apex in the range of 55.5 ppm to 60.0 ppm.
• the area P1 of peak 1 is positively correlated with the amount of aluminum substituted at silicon sites T3 to T9 among nine silicon sites T1 to T9 that exist equivalently in the crystal structure of BEA zeolite.
• the area P1 of peak 1 is the total area of the multiple peaks. It is presumed that the reason multiple peaks are observed is because aluminum in the process of being desorbed is detected.
• Peak 1 represents a peak derived from aluminum substituted at silicon sites T3 to T9 among nine silicon sites T1 to T9 that exist equivalently in the crystal structure of BEA zeolite.
• Peak 2 represents a peak derived from aluminum substituted at the T1 and/or T2 silicon sites among nine silicon sites T1 to T9 that exist equivalently in the crystal structure of BEA zeolite.
• the aluminum substituted at the T1 and/or T2 silicon sites is four-coordinate aluminum that is relatively difficult to function as an acid site, and the acid site adjacent to the Al atom formed by the four-range aluminum that is relatively difficult to function as an acid site is a relatively weak acid and has low acid strength.
• the area P2 of peak 2 is the total area of the multiple peaks. It is presumed that the reason multiple peaks are observed is because aluminum in the process of being desorbed is detected.
• the peaks having chemical shift values at the peak apex in the range of ⁇ 10.0 ppm to 10.0 ppm are peaks derived from 6-coordinate aluminum present outside the framework structure of the zeolite.
• the area ratio P1/(P1+P2) is a value that shows a positive correlation with the abundance ratio of aluminum that is likely to become a strong acid site that exhibits high acid strength and is substituted at silicon sites T3 to T9 relative to the total amount of aluminum substituted at nine silicon sites T1 to T9 in the BEA zeolite sample.
• the number of silicon sites T1 to T9 in one unit cell of BEA zeolite is 4 sites for T7 and T9, respectively, and 8 sites for T1 to T6 and T8, respectively.
• the total number of sites for T3 to T9 is 48 sites, and the total number of sites for T1 and T2 is 16 sites.
• the area ratio P1/(P1+P2) of the area P1 of peak 1 to the sum of the area P1 of peak 1 and the area P2 of peak 2 is in the range of 0.4 to 1.0, high acid strength is maintained and there are many Bronsted acid sites.
• the relationship between the BEA zeolite crystal structure and the 27 Al MAS NMR spectrum is described in the above-mentioned non-patent document Yoshihiro.
• the area ratio P1/(P1+P2) in the 27 Al MAS NMR spectrum of the BEA-type zeolite is in the range of 0.4 or more and 1.0 or less, preferably in the range of 0.5 or more and 0.95 or less, more preferably 0.6 or more, and may be 0.90 or less, or may be 0.85 or less.
• the pseudo-Voigt function f(x) used in peak separation of the pseudo-Voigt spectrum can be derived from the following formula (1).
• x represents the value on the horizontal axis of the NMR spectrum (chemical shift value)
• x0 represents the chemical shift value of the peak apex
• S represents a scaling coefficient for matching with actual measurement
• ⁇ represents the peak area ratio of the Lorentz function (first term) in the range from ⁇ (minus infinity) to + ⁇ (plus infinity)
• H and ⁇ represent the full width at half maximum of the peak
• ⁇ represents the constant of the circumference of a circle
• ln represents a natural logarithm function
• exp represents a natural exponential function.
• the obtained BEA type zeolite may be at least one type of zeolite selected from the group consisting of proton type BEA type zeolite ion-exchanged with hydrogen ions, sodium type BEA type zeolite ion-exchanged with sodium ions, and ammonium type BEA type zeolite ion-exchanged with ammonium ions.
• the obtained BEA type zeolite may be contacted with water or an aqueous solution containing sodium ions or ammonium ions to obtain each cation type BEA type zeolite, or the ammonium ion type BEA type zeolite may be heated to obtain proton type BEA type zeolite.
• the total molar amount of ammonium adsorbed on the acid sites of the BEA zeolite when the temperature is raised at 10° C./min by the ammonia temperature programmed desorption method (NH 3 -TPD method) relative to the molar amount of Al contained in the resulting BEA zeolite is preferably 0.30 mmol/Al-mmol or more. If the total molar amount of ammonium adsorbed on the acid sites relative to the molar amount of Al in the resulting BEA zeolite is 0.30 mmol/Al-mmol or more, this indicates that NH 3 is sufficiently adsorbed on the acid sites and that acid sites exhibiting high acid strength remain.
• the total ammonium molar amount adsorbed on the acid sites relative to the Al molar amount of the obtained BEA-type zeolite is more preferably 0.35 mmol/Al-mmol or more, even more preferably 0.38 mmol/Al-mmol or more, and is 1.8 mmol/Al-mmol or less, preferably 1.0 mmol/Al-mmol or less, more preferably 0.95 mmol/Al-mmol or less, may be 0.90 mmol/Al-mmol or less, or may be 0.85 mmol/Al-mmol or less.
• Zeolites having high acid strength and high crystallinity at a desired SiO2 / Al2O3 molar ratio can be used, for example, as catalysts in the petrochemical industry, hydrocarbon adsorbents, and exhaust gas purifying catalyst compositions containing hydrocarbon adsorbents.
• Exhaust gas purifying catalysts formed using the exhaust gas purifying compositions can be used as exhaust gas purifying catalysts for internal combustion engines such as gasoline engines and diesel engines.
• the catalyst, hydrocarbon adsorbent, and exhaust gas purification composition in the petrochemical industry containing the obtained zeolite can be formed into any form such as powder, paste, or granules and used.
• the exhaust gas purification composition can be used as a catalyst layer formed on a catalyst support.
• a support made of a ceramic or metal material can be used as the catalyst support.
• ceramics used as the catalyst support include alumina (Al 2 O 3 ), mullite (3Al 2 O 3 -2SiO 2 ), cordierite (2MgO-2Al 2 O 3 -5SiO 2 ), aluminum titanate (Al 2 TiO 5 ), and silicon carbide (SiC).
• metal materials used as the catalyst support include stainless steel.
• the shape of the catalyst support is not particularly limited, but examples include a honeycomb shape, a plate shape, and a pellet shape.
• a catalyst structure including an exhaust gas purification catalyst using an exhaust gas purification composition in the catalyst layer may include a catalyst layer made of a conventionally known catalyst material other than the exhaust gas purification composition.
• a catalyst structure using an exhaust gas purification composition in the catalyst layer can also be used as a DPF (Diesel Particulate Filter) or a GPF (Gasoline Particulate Filter).
• an OSDA-free BEA-type zeolite is prepared as follows.
• Tetraethylammonium hydroxide was used as the OSDA
• sodium aluminate was used as the alumina source
• powdered silica P707, manufactured by Mizusawa Chemical Industry Co., Ltd.
• the obtained BEA zeolite was fired in an electric furnace at 550°C for 10 hours while circulating air, to produce seed crystals containing no organic matter.
• the seed crystals did not contain an OSDA.
• an OSDA-free BEA zeolite was prepared as follows. An aqueous solution was obtained by dissolving 2.35 g of sodium aluminate and 18.28 g of 36 mass% sodium hydroxide in 139 g of deionized water. A mixture of 20.24 g of fine powder silica (M-5, manufactured by CABOT Corporation) and 2.02 g of the seed crystals was gradually added to the aqueous solution and stirred to obtain a reaction mixture having a composition with a SiO 2 /Al 2 O 3 molar ratio shown in Table 1.
• This reaction mixture was placed in a 60 mL stainless steel sealed container and heated at 140° C. for 46 hours under autogenous pressure without aging or stirring. After cooling the sealed container, the product was filtered and washed with warm water to obtain a white powder. It was confirmed by X-ray diffraction measurement described later that the white powder obtained was an OSDA-free sodium-type BEA-type zeolite (Na-BEA) containing no impurities. The SiO 2 /Al 2 O 3 molar ratio of the obtained OSDA-free BEA-type zeolite was measured using a scanning X-ray fluorescence analyzer described below. The results are shown in Table 1. In Tables 1, 2, and 3 shown below, "-" indicates that the corresponding item was not treated or that the corresponding value does not exist.
• OSDA-free ammonium type BEA type zeolite (NH 3 -BEA) 10 g of the obtained OSDA-free sodium type BEA type zeolite was dispersed in 300 mL of 2 mol/L ammonium nitrate aqueous solution. This dispersion was kept at 80°C for 24 hours. Thereafter, the dispersion was filtered, washed with a sufficient amount of distilled water, and dried overnight at 100°C. In this manner, OSDA-free ammonium type BEA type zeolite (NH 3 -BEA) was obtained.
• OSDA-free proton type BEA zeolite H-BEA
• OSDA-free ammonium type BEA zeolite was calcined at 600° C. for 2 hours in an ammonia atmosphere to obtain OSDA-free proton type BEA zeolite (H-BEA).
• zeolites used in Comparative Examples 4 and 5 were obtained by the same operations as those for producing the OSDA -free proton-type BEA -type zeolite (H- BEA ) used in Examples 1 and 2, except that the amounts of sodium aluminate and finely powdered silica were changed so as to obtain a reaction mixture having a composition with a SiO2/Al2O3 molar ratio shown in Table 1.
• each of the prepared BEA-type zeolites was mixed with pure water to obtain a zeolite mixture having a concentration shown in Table 1.
• the weight of each BEA-type zeolite shown in Table 1 is the weight in a dry state.
• the dry state here refers to a state in which the change (fluctuation range) in moisture content measured with a heat-drying moisture meter (MX-50, manufactured by A&D Co., Ltd.) is 0.01% or less.
• Sulfuric acid or nitric acid was used as the inorganic acid, and aqueous solutions of sulfuric acid or nitric acid having the concentrations and pHs shown in Table 2 were prepared.
• the zeolite mixture was set to each temperature shown in Table 2, placed in a flask, and an aqueous sulfuric acid or nitric acid solution was continuously supplied (dropwise) to the zeolite mixture while stirring in the amounts, rates, and times shown in Table 2.
• the zeolite was aged by contacting it with sulfuric acid or nitric acid for the time shown in Table 2 without separating the aqueous sulfuric acid or nitric acid solution from the zeolite.
• the total time for continuously supplying the aqueous sulfuric acid or nitric acid solution and the aging time is also shown in Table 2.
• Reference Examples 1 and 2 The prepared zeolites used in Reference Example 1 and Reference Example 2 were evaluated as described below. Note that in Reference Examples 1 and 2, no treatment using an inorganic acid was carried out.
• the entire amount of the aqueous sulfuric acid solution was supplied to the zeolite mixed solution at once, and then the zeolite was brought into contact with the sulfuric acid without additionally supplying the aqueous sulfuric acid solution, and aged for the time shown in Table 2. Since the entire amount of the aqueous sulfuric acid solution was supplied to the zeolite mixed solution at once, the time during which the aqueous sulfuric acid solution was continuously supplied was 0 hours, and the total time during which the aqueous sulfuric acid solution was continuously supplied and the aging time was the same as the aging time.
• Comparative Examples 4 and 5 The prepared OSDA-free proton type BEA zeolite was calcined in an air atmosphere at 800° C. for 20 hours to obtain a BEA zeolite. Note that in Comparative Examples 4 and 5, no treatment using an inorganic acid was performed.
• Comparative Example 6 The prepared zeolite used in Comparative Example 6 was evaluated as described below. Note that in Comparative Examples 4 and 5, no treatment using an inorganic acid was carried out.
• Zeolite framework structure The fact that the prepared zeolite is a BEA type zeolite was confirmed by measuring the X-ray diffraction spectrum of the zeolite obtained using a powder X-ray diffractometer. If there are diffraction peaks at diffraction angles 2 ⁇ of 8 ⁇ 1.5° and 22.8 ⁇ 1° in the X-ray diffraction spectrum using CuK ⁇ rays using a powder X-ray diffractometer, it can be confirmed that the zeolite is a BEA type zeolite.
• SiO2 / Al2O3 molar ratio of zeolite The amount of Si and the amount of Al in the measurement sample of each zeolite were measured by elemental analysis using a scanning X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku Corporation), and the SiO2 / Al2O3 molar ratio was calculated from the measured amount of Si and the amount of Al.
• the SiO2 / Al2O3 molar ratio was calculated from the amount of Si and the amount of Al in the measurement sample of each zeolite for both the zeolite to be prepared and the zeolite obtained after continuously supplying the solution containing an inorganic acid.
• NH 3 -TPD Method Ammonia Temperature Programmed Desorption Method
• NH 3 -TPD method ammonia temperature programmed desorption method
• the measurement was performed according to the following procedure. About 0.05 g of zeolite was pretreated by heating it to 500°C in He gas, holding it at 500°C for 10 minutes, and then cooling it to 100°C and holding it for 10 minutes. Next, at a sample temperature of 100°C, ammonia gas diluted with He gas (ammonia concentration in He is 5 vol%.
• 5% NH 3 -He 5% NH 3 -He
• 5% NH 3 -He 5% NH 3 -He
• the sample was purged in He gas for 30 minutes.
• the sample was heated from 100°C to 610°C at a heating rate of 10°C/min, and the amount of ammonia desorption was measured.
• the measurement device used was a catalyst analyzer BELCAT-II (manufactured by Microtrack Bell Co., Ltd.) and an online gas analyzer BELMass (manufactured by Microtrack Bell Co., Ltd.).
• the area of the TCD signal obtained by the measurement was calculated using waveform separation software ChemMaster (manufactured by Microtrack Bell Co., Ltd.).
• the area value of the TCD signal was converted to the amount of desorption of ammonia using a calibration curve utilizing the relationship between the flow rate and area when 5% NH 3 -He gas was flowed at a predetermined flow rate.
• peak separation was performed on the obtained TCD signal using the above-mentioned software. Peak separation was performed using the waveform decomposition function of the software.
• the TCD signal may have two or three peaks. The inventor speculates that each peak represents, from the low temperature side, physical adsorption, adsorption to acid sites, and desorption of structural water. In some cases, a peak representing desorption of structural water may not appear.
• Amount of acid (mmol)
• the TCD signal obtained by the above-mentioned NH 3 -TPD method was analyzed, and the area of the peak corresponding to adsorption to the acid sites (corresponding to the total molar amount of ammonium adsorbed to the acid sites of the BEA zeolite) was calculated to determine the amount of acid.
• Amount of acid per mole of Al (mmol/mmol of Al) The acid amount was calculated by dividing the above-mentioned acid amount by the molar amount of Al contained in the zeolite. The molar amount of Al was calculated using the measurement results of the SiO2 / Al2O3 molar ratio of the zeolite.
• Ratio A/B (crystallinity) An X-ray diffraction spectrum was measured by XRD using an X-ray diffractometer (Rigaku Corporation, RINT-TTR III) and a CuK ⁇ ray (0.15406 nm, 50 kV, 300 mA) as an X-ray source. The measurement was performed under the conditions of an angle 2 ⁇ of 5° to 80°, a scan speed of 20°/min, and a scan step width of 0.02°. The diffraction intensity was analyzed using the software "PDXL2". After removing the background, The diffraction peak intensity was obtained by fitting the K ⁇ 1 position to a split pseudo-Voigt function.
• the (111) plane was obtained from the X-ray diffraction spectrum of Si, which is the standard material 640c distributed by the National Institute of Standards and Technology.
• the peak intensity B of each zeolite was measured, and the maximum diffraction intensity A of the peak was calculated from the X-ray diffraction spectrum of each zeolite of the Examples, Reference Examples, and Comparative Examples.
• zeolites with high acid strength were obtained, in which the apex temperature in the NH 3 -TPD spectrum measured by ammonia temperature programmed desorption method was in the range of 340° C. or more and 500° C. or less.
• the SiO 2 /Al 2 O 3 molar ratio of the obtained zeolites was in the range of 13 or more and 1000 or less, and zeolites having a wide range of SiO 2 /Al 2 O 3 molar ratios were obtained.
• the ratio A/B of the obtained zeolites was 25 or more, and a high degree of crystallinity was maintained.
• the zeolite obtained had an area ratio P1/(P1+P2) of 0.4 to 1.0, and contained a large amount of 4-coordinate Al that easily functions as an acid site, and therefore had high acid strength.
• the zeolite prepared was a BEA type zeolite. Regardless of whether a proton type BEA type zeolite, a sodium type BEA type zeolite, or an ammonium type BEA type zeolite was used, zeolites having a wide range of SiO2 / Al2O3 molar ratios were obtained while maintaining high acid strength and high crystallinity.
• the zeolite obtained had a total ammonium molar amount adsorbed on the acid sites of the zeolite when the temperature was raised at 10°C/min by the ammonia temperature programmed desorption method ( NH3 -TPD method) of 0.30 mmol/Al-mmol or more relative to the Al molar amount contained in the zeolite, and thus had acid sites exhibiting high acid strength.
• NH3 -TPD method ammonia temperature programmed desorption method
• the zeolite manufacturing method of the present disclosure can adjust the SiO 2 /Al 2 O 3 molar ratio while maintaining high acid strength and high crystallinity.
• the zeolite obtained by the zeolite manufacturing method of the present disclosure has high acid strength and high crystallinity over a wide range of SiO 2 /Al 2 O 3 molar ratios, and can be suitably used as a catalyst in the petrochemical industry or a catalyst for purifying exhaust gas.

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